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a section of a computer program that is stored only once but can be used when required at several different points in the program, thus saving space



the part of a computer program that is used to solve similar-type problems. A subroutine usually describes a separate step in the computation process and can be used more than once in one or several different programs. Typical subroutines are used to compute elementary functions, such as sin x, In x, and e-x, to solve systems of equations, and to remove the results of computations in various forms. If it becomes necessary to use the subroutine during the running of the basic program, the subroutine is called at the appropriate place in the program, and after it has been run, control is transferred back to the main program. A subroutine can call on another.

A subroutine should have the following characteristics: it should be subject to standardized access rules that make it possible to call the subroutine from the main program by means of one or more instructions; it should be able to work with a broad range of initial data, for example, independent variables of a function; it should be relocatable, that is, it should be possible to place and run it in various parts of the computer memory. Subroutines are often arranged in subroutine libraries. So-called standard subroutines satisfying rigid conditions are used in automatic programming.

The use of subroutines is one way to save time and effort in writing computer programs. Subroutines form the basis of modular programming.


Lavrov, S. S. Vvedenie v programmirovanie. Moscow, 1973. (Bibliography.)



(computer science)
A body of computer instruction (and the associated constants and working-storage areas, if any) designed to be used by other routines to accomplish some particular purpose.
A statement in FORTRAN used to define the beginning of a closed subroutine (first definition).


(Or "procedure") A sequence of instructions for performing a particular task. Most programming languages, including most machine languages, allow the programmer to define subroutines. This allows the subroutine code to be called from multiple places, even from within itself (in which case it is called recursive). The programming language implementation takes care of returning control to (just after) the calling location, usually with the support of call and return instructions at machine language level.

Most languages also allow arguments to be passed to the subroutine, and one, or occasionally more, return values to be passed back.

A function is often very similar to a subroutine, the main difference being that it is called chiefly for its return value, rather than for any side effects.


A group of instructions that perform a specific task. A large subroutine might be called a "module" or "procedure." Subroutine is somewhat of a dated term, but it is still quite valid.
References in periodicals archive ?
3) Separate the computations from the subroutines, which required executing only once;
A potential mistake in acquisition planning is overlooking the fact that the subroutines and modules used to create applications and environments may either have a more individually unique scope or a broader scope than the application to which they belong.
Once it begins, click on Insert, then Module to open a VBA screen; that's the place where you will write the VBA code, which is technically called the subroutine or subprocedure.
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In Wittmann's CANbus CNC controls, all the robot programs and related subroutines run simultaneously on the different microprocessors.
Readers can then obtain copies of the videos "for some rather minimal cost," Landman says, or download the raw data - together with related computer programs and subroutines - free of charge from a pair of new electronic bulletin boards.
In each case the command allows the batch file to branch to subroutines located inside it.
U2 Basic subroutines can now be used as methods in the dataset designer and entity model.
Beginning with an overview of number systems, operations, and codes, the volume explores topics such as semiconductors and digital logic, microcontroller software, control structures and subroutines, input/output ports, interrupts, and input capture methods.
This application allows linking the created inference engines with subroutines (one subroutine for each defect).
Examples and homework problems, many new for this second edition, are included, with a solutions manual available separately, along with about 30 reference pages of theorems, proofs, transformations, subroutines, and coefficients.
the new subroutines package specially written to help speedup the commissioning and increase the day-to-day operating efficiency of ICL igoo series computers, is now available from 1900 Programming Ltd.